Process for developing radiation-sensitive elements

ABSTRACT

PHOTOGRAPHIC DYE IMAGES CAN BE PRODUCED BY PHYSICAL DEVELOPMENT OF IMAGEWISE EXPOSED ELEMENTS CONTAINING A RADIATION-SENSITIVE METAL COMPOUND TO FORM AN IMAGEWISE DISTRIBUTION OF CATALYST. THE RESULTANT CATALYST IMAGE IS THEN TREATED IN THE PRESENCE OF A COLOR DEVELOPER AND A COLOR COUPLER WITH AN AMPLIFIER SOLUTION CONTAINIG A COBALT (III) COMPLEX HAVING A COORDINATION NUMBER OF SIX, WHEREIN SAID TREATMENT IS ACCOMPLISHED UNDER CONDITIONS WHICH REDUCE COBALT (III) TO COBALT (II) AND, IN TURN, OXIDIZE THE COLOR DEVELOPER TO THEREBY FORM IMAGE DYE FROM THE OXIDIZED COLOR DEVELOPER AND THE COLOR COUPLER.

United States Patent O 3,826,652 PROCESS FOR DEVELOPING RADIATION-SENSITIVE ELEMENTS Vernon L. Bissonette, Brockport, N.Y., assignor tEastman Kodak Company, Rochester, N.Y.

No Drawing. Continuation-impart of application Ser. No. 189,289, Oct.14, 1971. This application Dec. 4, 1972, Ser. No. 312,169

Int. Cl. G03c 1/5=8, 5/22, 5/24, 5/32, 5/34, 7/00 US. Cl. 9648 PD 28Claims ABSTRACT OF THE DISCLOSURE Photographic dye images can beproduced by physical development of imagewise exposed elementscontaining a radiation-sensitive metal compound to form an imagewisedistribution of catalyst. The resultant catalyst image is then treatedin the presence of a color developer and a color coupler with anamplifier solution containing a cobalt(lII) complex having acoordination number of six, wherein said treatment is accomplished underconditions which reduce cobalt(III) to cobalt(II) and, in turn, oxidizethe color developer to thereby form image dye from the oxidized colordeveloper and the color coupler.

This is a continuation-in-part application of Bissonette US. ApplicationSer. No. 189,289, filed Oct. 14, 1971.

FIELD OF INVENTION This invention relates to the art of photography andmore particularly, to a process for developing photographic elementswhich comprise layer units containing a photosensitive metal compoundthat forms catalytic sites for the deposition of metal from a physicaldeveloper composition and optionally contain an image dye-provid ingphotographic color coupler associated with said compound.

DESCRIPTION OF THE PRIOR ART It is known in the prior art to physicallydevelop exposed silver halide emulsions to thereby render the latentimage visible. Typical physical developer solutions contain a reduciblemetal compound and a reducing agent. In physical development, virtuallyall the metal in the resultant visible image is formed by the selectivereduction of metal ions supplied by the reducible metal compound duringdevelopment. Once a catalytic site (e.g., the latent silver imagespecks) is enveloped with metal deposited from the developer solution,it is essential that the reduced metal be autocatalytic, that is, it toomust catalyze the decomposition of the physical developer solution.

Physical development involving silver compounds has not had anysubstantial commercial application due to the instability of silverphysical developer solutions. Thus, shortly after a physical developersolution is prepared by mixing silver salts and reducing agent, reducedsilver begins to deposit rapidly and in a few hours the developersolution is completely decomposed. This type of instability is inherentin silver physical developer solutions, since the poor autocatalyticproperties of silver metal require that silver physical developersolutions be formulated so as to be capable of depositing silver veryrapidly, if inordinately long development times are to be avoided.

These problems have been overcome through the use of non-silver imagingelements and appropriate developer solutions therefor. Elements andprocesses of this type are described, for example, in Yudelson U.S. Pat.No. 3,597,206, issued Aug. 3, 1971. However, such physical developmentprocedures typically are neutral density monochrome systems. Dippell etal. in US. Pat. No. 2,750,292, issued June 12, 1956, earlier describedwhat was referred to as a means for producing colored images by physicalcolor development. This latter system was lengthy in that it requiredseparate sequential exposure and development steps for each colordesired. Each development step alone required anywhere from three to tenminutes. Typical solutions for color formation contain bothcolor-developing agent and a color coupler. Solutions of this type areprone to formation of dye in the bath through aerial oxidation of thedeveloper, causing dye contamination; additionally, systems using these7 solutions are often limited to one color. Moreover, where a physicaldeveloping agent is used in conjunction with a color coupler and acolor-developing agent, the processing baths themselves are oftenautocatalytic since the reaction products of the redox reaction with thephysical development provide a catalyst for more redox reactions.

New processes for developing and amplifying an image record aredisclosed in Bissonette US. Application Ser. No. 189,289, entitledImage-Forming Processes and Compositions, filed Oct. 14, 1971, and inTravis U.S. Application Ser. No. 256,071, entitled Process forDeveloping Photographic Elements, filed May 23, 1972, now US Pat. No.3,765,891, both incorporated by reference herein. In one embodiment, theprocesses disclosed therein relate to image formation in photographicelements comprising color-providing layer units containing a silverhalide emulsion having associated therewith a color coupler. While suchprocesses are excellent for forming color images from silver halideemulsions, they typically involve the use of only chemical developmentin the formation of visible images.

Accordingly, there is a need in the art for a relatively simple meansfor obtaining colored images through the use of physical development.

SUMMARY OF THE INVENTION I have found that photographic dye images canbe produced, using physical development techniques, by first physicallydeveloping an imagewise exposed element containing 21radiation-sensitive metal compound to form an imagewise distribution ofcatalyst. The resultant catalyst image is then treated, in the presenceof a color developer and a color coupler, with an amplifier solutioncontaining a cobalt(III) complex having a coordination number of 6, saidtreatment being accomplished under conditions which reduce cobalt(Ill)to cobalt(II) and, in turn, oxidize the color developer to thereby formimage dye from the oxidized color developer and the color coupler.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The objects of the presentinvention are achieved through the use of a photographic elementcomprising a support having thereon at least one color-providing layerunit containing a radiation-sensitive compound of a first metal, whichcompound, upon exposure to actinic radiation, forms catalytic sites forthe deposition of a second metal from a physical developer composition.In a preferred embodiment, said compound has associated therewith animage dye-providing color coupler. An element of this type is imagewiseexposed to form a latent image of catalytic sites for physicaldevelopment. After exposure, the element is subjected to a physicaldeveloper composition, for example, by immersing the element in anaqueous solution of the physical developer. After physical development,the resultant imagewise distribution of catalyst is treated with anamplifying bath in the presence of a color-forming reducing agent and acolor coupler to eflect a catalyzed redox reaction between an oxidizingagent and a color-forming reducing agent whereby said reducing agent isoxidized and combines with the color coupler to form an image dye in theareas corresponding to said catalyst.

Generally, the photographic elements in accordance with this inventioncomprise any suitable support such as those known in the photographicart. Carried on that support is at least one and preferably two or morecolorproviding layer units which can contain a wide variety of metalcompounds which, upon exposure, form sites for further physicaldevelopment. Materials of this type include metal compounds which yieldphotolytically produced metal latent image sites (such as metal imagesof silver, gold, copper, iron, tin, mercury, palladium, etc.), as wellas those which merely form an electronic charge latent image such asvarious photoconductors known in the art. The former type of metalcompounds include various silver salts (e.g., halides, oxalates, etc.),as known in the art as well as a variety of non-silver metal salts, suchas oxalate, citrate, etc., salts of a Group VIII, Group lb or Group IIbmetal, e.g., palladium oxalate, ferric ammonium oxalate, mercuryoxalate, ferric ammonium citrate and the like. Non-silver salts of thistype and their use are described in U.S. Pat. No. 2,750,292, issued June12, 1956, U.S. Pat. No. 3,597,206, issued Aug. 3, 1971 and British Pat.No. 1,265,844, dated Mar. 8, 1972. Various useful photoconductivecompounds include metal oxides, such as titanium dioxide, antimonytrioxide, zirconium dioxide, germanium dioxide, indium oxide, stannicoxide, barium titanate, lead oxide, tantalum oxide, and tellurium oxide;metal sulfides such as cadmium sulfide, zinc sulfide and stannicsulfide; and metal selenides, such as cadmium selenide. Inorganicphotoconductors of this type are described further in U.S. Pat. No.3,121,- 006, issued Feb. 11, 1964. Some of these materials are sensitiveto radiation outside the visible region of the spectrum. For example,certain lead oxides are sensitive to X-radiation. Preferredphotoconductive compounds for use in this invention are oxides andsulfides of Group IIb, IVb or IVa metals. Highly preferred are metaloxides, with titanium dioxide providing good results. Thus, preferredphotosensitive metal compounds for use herein contain a Group Ib, IIb,IVb, IVa or VIII metal atom as seen in the Periodic Chart of theelements found on page 30 of Cotton and Wilkinson Advanced InorganicChemistry, 1962 Edition.

In preferred embodiments, especially multicolor embodiments, there is acolor coupler associated with the radiation-sensitive metal compound.The terms photographic color coupler and image dye-providing colorcoupler include any compound which reacts (or couples) with theoxidation products or primary aromatic amino developing agent onphotographic developemnt to form an image dye, and are nondiffusible ina hydrophilic colloid binder (e.g., gelatin) useful for photographicsilver halide, and also those couplers which provide useful image dyeswhen reacted with oxidized primary aromatic amino developing agents suchas by a coupler-release mechanism. The couplers can form diffusible ornondiffusible dyes. In those instances of dilfusi'ble dye formation, theresultant dye is generally imagewise transferred to a receiver sheet.Typical preferred color couplers include phenolic, 5-pyrazolone andopenchain ketomethylene couplers. Specific cyan, magenta and yellowcolor couplers which can be employed in the practice of this inventionare described in Graham et a1. U.S. Pat. No. 3,046,129, issued January24, 1962, Column 15, line 45, through Column 18, line 51, whichdisclosure is incorporated herein by reference. Such color couplers canbe dispersed in any convenient manner, such as by using the solvents andthe techniques described in U.S. Pats. 2,322,027 by Jelley et al.,issued June 15, 1943, or 2,801,171 by Fierke et al., issued July 30,1957. When coupler solvents are employed, the most useful weight ratiosof color coupler to coupler solvent range from about 1:3 to 1:0.1. Theuseful couplers include Fischertype incorporated couplers such as thosedescribed in Fischer U.S. Pat. 1,055,155, issued Mar. 4, 1913, andparticularly nondiffusible Fischer-type couplers containing branchedcarbon chains, e.g., those referred to in the references cited inFrohlich et al., U.S. Pat. No. 2,376,- 679, issued May 22, 1945, Column2, lines 50-60. Particularly useful in the practice of this inventionare the nondiffusible color couplers which form nondiffusible dyes.

In certain preferred embodiments, the incorporated coupiers in the layerunits of this invention are waterinsoluble color couplers which areincorporated in a coupler solvent which is preferably a moderately polarsolvent. Typical useful solvents include tri-o-cresyl phosphate,di-n-butyl phthalate, diethyl lauramide, 2,4-diarylphenol, liquid dyestabilizers as described in an article entitled Improved PhotographicDye Image Stabilizer- Solvent, Product Licensing Index, Volume 83, pages26 29, March 1971, and the like.

The light-sensitive metal compounds are generally coated in thecolor-providing layer units in the same layer with the photographiccolor coupler. However, they can be coated in separate adjacent layersas long as the coupler is effectively associated with the respectivephotosensitive layer to provide for immediate dye-providing reactions totake place before substantial color developer oxidation reactionproducts diffuse into adjacent colorproviding layer units. A multicolorphotographic element comprises at least two of said image dye-providinglayer units each of which primarily records light in a different regionof the spectrum. The layer unit comprises a lightsensitive metalcompound, which can be spectrally sensitized to a specific region of thespectrum, and a photographic color coupler associated with saidcompound. In certain preferred embodiments, the color-providing layerunits are continuous layers which are effectively isolated from otherlayer units by barrier layers, spacer layers, layers containingscavengers for oxidized developer and the like to prevent anysubstantial color contamination between the image dye-providing layerunits. The effective isolation of the layer units is known in the artand is utilized to prevent contamination in many commercial colorproducts.

The concentration of coupler can vary widely. In preferred embodiments,the coupler concentration is in excess over the amount of photosensitivemetal compound present. In certain preferred embodiments, thephotographic color couplers are employed in the image dyeproviding layerunits at a concentration of at least about 3 times and up to about 20times the weight of photosensitive material present in that layer unit.Weight ratios of coupler to metal compound which are particularly usefulare from 4 to 15 parts by weight of coupler to 1 part by weight of metalcompound. Advantageously, the coupler is present in an amount sufiicientto give a density of at least 1.7 and preferably at least 2.0.Preferably, the difference between the maximum density and the minimumdensity (which can comprise unbleached metal) is at least .6 andpreferably at least 1.0.

It is realized that the density of the dye may vary with the developingagent combined with the respective coupler, and accordingly, thequantity of coupler can be adjusted to provide the desired density.Preferably, each layer unit containing coupler contains at least 1X10-moles/ft. of color coupler.

Advantageously, the photographic color couplers utilized are selected sothat they will give a good neutral dye image. Prefer-ably, the cyan dyeformed has its major visible light absorption between about 600 and 700nm., the magenta dye has is major absorption between about 500 and 600nm., and the yellow dye has its major absorption between about 400 and500 am.

After exposure of the described elements, they are treated with aphysical developer composition to deposit imagewise a catalyticallyactive metal such as a Group VIII, Group.VIa or Group Ibmetal whichtypically is different from the metal of said photosensitive compound.Useful physical developer compositions contain as the majorpactiveingredient. anionizable salt of a Group Ib, VIa or VIII metal. Physicaldeveloper solutions for use with elements containing a photosensitivemetal compound which upon-exposure yields photolytically producedmetallatent image sites, typically comprise a reducible heavy metal. salt(e.g., a reducible salt of such metals as-mickel, cobalt, iron, chromiumor copper), a reducing agent for the heavy metal salt (e.g.,formaldehyde, sodium hypophosphite, sodium hydrosulfide or potassiumborohydride), and a complexing agent for heavy metal ions derived fromthe reducible heavy metal salt (e.g., a carboxylic acid such as maleicacid, lactic acid, citric acid, aspartic acid or glycolic acid). Suchphysical developers are extremely stable'under storage conditions, butin the presence of catalytic centers are reduced and deposit heavy.metal .onthe catalytic sites. Physical developer compositions of thistype as well as the formulation thereofare described, for example, inUS. Pat. No. 3,597,206 which is incorporated herein by reference.

In those-=instances.wherein' the photosensitive metal compound used is aphotoconductor as described previously,.' the deposition ofa-catalytically active Group Ib, VIa or V-III metal can be accomplishedin a variety of ways.;For example, a solution of a suitable metal saltcan-be applied to the exposed element whereby the trapped electron-holepairs produced in the exposed areas of the photoconductorinteract withthemetal ions in solution to' cause .imagewise' deposition of metal.Additionally, various electrolytic deposition techniques can be used asdescribed,'for example, in US. Pat.'No. 3,372,029, issued Mar. 5, 1968.

The term physical development as used in connection with this inventionhas reference to any means for imagewise depositing a catalyticallyactive Group Ib, VIa or VII I metal including-the various'means known inthe art of photoconductography (e.g., see US. Pat. No. 3010,8815, issuedNov. 28, 196 1 )1 Physical development also refers tothjelphysicaldeposition of'metalto form a subvisible or 'or'ilypartially'vi'sible image. The'resultant physically developed image neednot be visible to be useful as it serves as a catalyst for a subsequentdye formation reaction. The physical developer for i the photosensitiveelements of this invention can, of course, be applied from a rupturablepod which optionally can be an integral part of the element.

The photographic elements described herein are subsequently treated bythe processes disclosed in Bissonette UJS. Ser. No. 189,289, entitledImage-forming Processes and Compositions, Ifiled Oct. 14, 1971, andincorporated herein by reference. Generally, in this process, a redoxreaction between an oxidizing agent and a reducing agent is utilized toproduce a change in light value. This change in light value can comeabout directly by a change in the light value of either the oxidizingagent or reducing agent. Alternatively, the redox reaction can result inone or more reaction products which can react with each other or withanother component, such as a reactive species, to produce a change inlight value. In another variation, the reactivity of the reactivespecies can be reduced imagewise by one of the reaction products of theredox reaction.

The redox reaction which takes place when the elements are processed bythis procedure occurs at the catalytic surface provided by the metaldeposited from the physical developer solution. The catalyst appears topromote redox reaction in true catalytic fashion. The amount of redoxreaction products is not: limited by the amount of catalyst present,since the catalyzed redox reaction of this invention does not proceed ona stoichiometric basis with respect to the catalyst.

Oxidants preferred in the practice of this process are the metalcomplexes, such as a transition metal complex. Preferred metal complexesin accordance with this process have coordination numbers of six and areknown as octahedral complexes. A wide variety of ligands can be usedwith a metal ion to form suitable metal complexes. Nearly all Lewisbases (i.e., substances having an unshared pair of electrons) can beligands in metal complexes. Some typical useful ligands include thehalides, e.g., chloride, bromide, fluoride, nitrite, water, amino, etc.,as well as such common ligands as those referred to by Basolo andPearson in Mechanisms of Inorganic Reactions, a Study of Metal Complexesand Solutions, 2nd Edition, 1967, published by John Wiley and Sons, page44. The lability of a complex is influenced by the nature of the ligandsselected in forming said complex.

Particularly useful cobalt complexes have a coordination number of 6 andhave a ligand selected from the group consisting of ethylenediamine(en),diethylene-triamine( dien) triethylenetetraamine( trien) ammine NHnitrate, nitrite, azide, chloride, thiocyanate, isothiocyanate, water,carbonate, and propylenediamine(tn). The preferred cobalt complexescomprise (I1) at least 2 ethylene diamine ligands or (2) at least 4ammine ligands or (3) 1 triethylenetetraamine ligand. Especially usefulare the cobalt hexammine (e.g., the chloride, bromide, sul fite,sulfate, perchlorate, nitrate, nitrite and acetate salts). Some otherspecific highly useful cobalt complexes include those having one of thefollowing formulas:

wherein X represents one or more anions determined by the chargeneutralization rule. Complexes containing oxidized noble metals orferromagnetic metals, such as complexes of Cr Fe Rh Pt Pd and Ir whichhave reactivities similar to the complexes listed above, could be usedin the practice of this invention. The redox equilibra published inStability Constants of Metal-Ion Complexes, Sillen and Martell,published by The Chemical Society, Burlington House, London, England(1964), indicate that other complexes have reactiv- ItlJBS generallysimilar to the cobalt complexes mentioned a ove.

Numerous reducing agents can be utilized in carrying out the sameprocess. The reducing agents utilized herein undergo redox reaction withthe oxidizing agent at a catalytic surface. In certain embodiments, thereducing agent used in this process is an aromatic primary aminocolor-developing agent such as p-phenylenediamine. Color-developingagents which can be used include 3-acetamtdo-4-amino-N,N-diethylaniline,4-amino-N-ethyl-N-B- hydroxyethylaniline sulfate,N,N-diethyl-p-phenylenediamine, Z-amino-S-diethylaminotoluene,N-ethyl-N-B-methanesulfonamidoethyl-3-methyl-4-aminoaniline, 4 amino-N-ethyl-3-methyl-N-(,B-sulfoethyl)aniline, and the like. See Bent et a1JACS, Volume 73, pp. 3100-3125 (1951), and Mees and James, The Theory ofthe Photographic Process, 3rd Edition, 1966, published by Macmillan Co.,New York, pp. 278-311, for further typical, useful developing agents.

In one highly preferred embodiment, aromatic primary aminocolor-developing agents which provide good results in this process are4-amino-N,N-diethylaniline hydrochloride,4-amino-3-methyl-N,N-diethylaniline hydro chloride,4-amino-3-methyl-N-ethyl-N-fl-(methanesulfonamido)ethylaniline sulfatehydrate, 4-amino-3-methyl-N- ethyl-N-B-hydroxyethylaniline sulfate,4-amino-3-methylamino-N,N-diethylaniline sulfate hydrate, 4-arnino-3-me-7 thoxy-N-ethyl-N-B-hydroxyethylaniline hydrochloride, 4-amino-3-,B-(methanesulfonamido)ethyl N,N diethylaniline dihydrochlorideand 4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine-di-p-toluenesulfonate.

In one embodiment, the amplifier solution of oxidizing and reducingagents can be imbibed into an applicator sheet, such as a gelatin coatedsupport, and placed in faceto-face contact with the physically developedphotosensitive element in the presence of an activator solution. Asuitable activator would include an aqueous alkaline solution. Also, theactivator solution can be a viscous medium which can be applied betweenthe applicator sheet and the element through the use of a rupturablepod.

The following examples are included for a further understanding of theinvention.

Example 1 (0.3 g. K Pd(C O in 100 ml. H O).

Elemental analysis shows that a 5-minute imbibition in the abovesolution gives a palladium oxalate coverage of 5-10 mg./ft. Upon dryingit is exposed to a graduateddensity test object using radiation in therange of 360 to 440 nm. The sample is then nickel physically developedin a solution of the following composition:

G. NiCl -6H O 23.8 NaH2PO2 Gluconic Acid (50% in H O) 225 H O to 1liter. (pH adjusted to 5.0 with NaOH, then to 9.0 with NH OH) Afterphysical development, the sample is washed, then color developed indeveloper of the following composition:

K CO 30 K 50 2.0 4 amino N ethyl N(2 methoxyethyl) mtoluidinedi-p-toluenesulfonate [Co(NH ]Cl 1.6

H 0 to 1 liter; pH 10.1 with 10% HCl. The exposure and processingconditions are as follows:

Exposure min 1 3 Nickel physical development sec 10 H O Wash sec 10Color Developer min 10 H O Wash min 3 considerably more than sufiicientto fog silver chloride Example 2 A melt of the following composition ishand-coated at a wet thickness of .006 inches onto a support:

H O ml 10 TiO g 2 Gelatin (12.5% aqueous solution) ml 7 Saponin (7%aqueous solution) (spreading agent) Formalin (5% aqueous solution)(hardener) ml 1 Green sensitizing dye (merocyanine, .6 mg./ml.)

drops 3 The above light-sensitive layer is then overcoated at a wetthickness of .006 inches with a melt of the following composition:

Ml. Gelatin (12.5% aqueous solution) 9.4 Saponin (7% aqueous solution)2.5

Coupler of Example 1 (6% dispersion in tricresyl phosphate) 5.4 2 20Formalin (5% aqueous solution) 2.5

A strip of the dual-layer element thus prepared is exposed for 15seconds with a low-output U.V. lamp through a line-copy test sample andthen immersed for 2 minutes in an approximately 1% aqueous silvernitrate solution. The strip is washed for 1.5 minutes and then treatedfor 2 minutes at room temperature in the developer/amplifier solutionthe composition of which is shown below. After fixing in a Kodak F-5sodium thiosulfate fixing solution (see page 3315 of Handbook ofChemistry and Physics, 41st Edition), washing, and final drying, thestrip contains a negative magenta dye image reproduction of thephotographic test sample. A similar element is exposed and treated withAgNO in the same manner as above, followed by treatment for 1 minute inthe Kodak F-S fixing solution, washing for 2 minutes and treatment inthe developer/amplifier bath. A good dye image results. A repeat of theabove described procedure with a developer/amplifier solution which doesnot contain cobalt hexammine does not yield a good visible dye image.

Composition of Developer/Amplifier Solution Benzyl alcohol ml 15 K2CO3..g KBr g 0.7 Hydroxylamine sulfate g 2 K g 4 Diaminopropanoltetraacetic acid g 3 Color Developing Agent (4-amino-N-ethyl-N-(2-methoxyethyl)-m-toluidine, di-ptoluenesulfonate) g 7.5 [C0(NH3) ]Cl3 gWater liters to 1 Example 3 A sample of a supported single-layer gelatincoating containing per square foot of coating 200 mg. gelatin, 5 mg. KFe (C O -3H O, and 168 mg. of the magenta-dyeforming coupler of Example1 dissolved in di-n-butylphthalate is exposed for 5 minutes at adistance of 12 inches to a 1000 watt quartz iodide lamp through agraduated density test object and then processed in the followingmanner:

Sec.

Treatment in 1% aqueous K [Fe(CN) solution 30 Wash 30 Treatment in 1%aqueous AgNO 30 Wash 30 Treatment in the amplifier solution described inExample 2 Wash. Dry.

This procedure results in a magenta colored reproduction of thephotographed test object. A control test without [Co(NH ]Cl in theamplifier solution produces no y image v.. ...l

Example 4 A coating dope of the following composition is pre pared:

G. Binder-Resin Mix A 53.3 Pigment-Zir1c oxide XX-78 (New Jersey ZincCo.) 62.2 Solvent-Toluene 76.8 Surfactant -Solution B 3.92

Resin Mix A G. Pliolite S7 (Goodyear Tire & Rubber Co.) 444.5 SiliconeSR-SZ (General Electric Company) 27.8 Piccopale (Penn. Ind. Chem.Company) 27.8

Surfactant Solution B A solution of eight grams of a mixture of 1 partAerosol TR (a bis(tridecyl) ester of N-sulfosuccinic acid from AmericanCyanamid) and 3 parts Duomeen-S (an N-tallow trimethylene diamine saltfrom Armour Industrial Chemical Company) in a 4:1 solvent mixture oftoluene and methanol.

The resultant dope is ball milled for 48 hours and then coated at a wetthickness of 0.008 inch on an aluminum foil-paper laminate. The coatingis then exposed for 50 seconds to a Rayonet UV light source at adistance of 12 inches through a line-copy test object and then contactedwith a negative electrode consisting of an 18% aqueous solution of AgNOwith a potential of 50 volts. Thereafter, the coating is immersed for 1minute at a temperature of 24 C. (75 F.) in an amplifier-developersolution having the following composition:

Cyan-dye-forming coupler 1-hydroxy-2- fl- 2'-acetamido)-phenethyl]naphthamide g 4.0 Ethanol ml 50 20% NaOH ml 50 Benzyl alcoholml l K 80 g 2 KBr g 2.5 Na EDTA g 5.0 [CO(NH3)5]CI3 g.. Color developingagent N-ethyl-N- B-methoxyethyl)-3-methyl-p-phenylenediamine,di-ptoluenesulfonate g 3.0 K2CO3 g.....

H O to 1 liter.

After a brief rinse with water, the coating is dried. It contains anamplified negative rendition in cyan dye of the photographed testobject.

Example 5 When the procedure described in Example 4 is repeated withanother sample of the coating and an amplifier-developer solutionwherein the cyan-dye-forming coupler is replaced with theyellow-dye-forming coupler u-benzoyl-Z-methoxyacetanilide, an amplifiednegative rendition in yellow dye of the photographed test object isobtained.

Example 6 When the procedure described in Example 4 is repeated withanother sample of the coating and an amplifier-developer solutionwherein the cyan-dye-forming coupler is replaced with themagenta-dye-forming coupler 1-(2,4,6-trichlorophenyl)-3-(4-nitroanilino) S-pyrazolone, an amplifiednegative rendition in magenta dye of the photographed test object isobtained.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be affected within the spirit and scopeof the invention.

I claim:

1. A process of providing or intensifying a visible image in aphotographic element which comprises at least one color-forming layerunit containing a radiation-sensitive compound of a first metal whichcompound upon exposure to actinic radiation forms catalytic sites forthe deposition of a second metal from a physical developer composition,said process comprising the steps of (1) imagewise exposing said elementto actinic radiation, (2) treating said element with a physicaldeveloper comprising a solution of an ionizable salt of a second metalto imagewise deposit said second metal on said element, (3) contactingthe resultant element with an amplifier com position in the presence ofa color-developing agent and a color coupler, said compositioncontaining a cobalt(III). complex having a coordination number of six,wherein said contact is maintained under conditions which reducecobalt(III) to cobalt(II) and, in turn, oxidize said color developingagent whereby image dye is formed from the color coupler and theoxidized color developing agent in proportion to the imagewisedistribution of said second metal.

2. A process as described in claim 1 wherein said color-developing agentis an aromatic primary amino compound.

3. A process as described in claim 1 wherein said second metal isdifferent from said first metal.

4. A process as described in claim 1 wherein said photographic elementcomprises at least two of said colorproviding layer units.

5. A process as described in claim ll wherein the colored coupler isassociated with said compound in the color-forming layer unit.

6. A process as described in claim 5 wherein each of saidcolor-providing layer units comprises said color coupler in aconcentration sufiicient to produce a dye density of at least about 1.7.

7. A process as described in claim I wherein said compound is aphotosensitive salt of a Group VIII metal.

8. A process as described in claim 1 wherein said physical developercomprises an aqueous solution of a reducible salt of a heavy metalselected from the group consisting of a Group Ib metal, a Group VIametal, a Group VIII metal and mixtures thereof, a reducing agent forheavy metal ions derived from said salt and a com plexing agent forheavy metal ions derived from said salt.

9. A process as described in claim 1 wherein said compound is aphotosensitive salt of a Group Ib metal.

10. A process as described in claim 1 wherein said compound is an oxideor sulfide of a Group III; metal.

11. A process as described in claim 1 wherein said compound is an oxideor sulfide of a Group IVb metal.

12. A process as described in claim I. wherein said compound is an oxideor sulfide of a Group IVa metal.

13. A process as described in claim 1 wherein said radiation-sensitivecompound is titanium dioxide.

14. A process of providing or intensifying a visible image in aphotographic element which comprises at least one color-forming layerunit containing a photosensitive metal salt containing a Group Ib, IIbor VIII metal which upon exposure to actinic radiation forms catalyticsites for the deposition of metal from a physical developer composition,said compound having associated therewith an image dye-providingphotographic color coupler, said process comprising the steps of ('1)imagewise exposing said element to actinic radiation, (2) treating saidelement with a physical developer comprising a reducible heavy metalsalt containing a Group Ib, VIa or VIII metal, a complexing agent forheavy metal ion derived from said salt and a reducing agent for heavyions derived from said salt, (3) contacting the resultant physicallydeveloped element in the presence of a color-developing agent with anamplifier composition which contains a cobalt (III) complex having acoordination number of six, wherein said contact is maintained underconditions which reduce cobalt(III) to cobaltfll) and in turn oxidizesaid -1 1 color developing agent whereby image dye is formed from thecolor coupler in said layer unit and the oxidized color developing agentin the areas corresponding to the imagewise distribution of physicallydeposited heavy metal.

15. A process as described in claim 14 wherein .said photosensitivemetal salt is a metal oxalate.

16. A process as described in claim 14 wherein said reducible heavymetal salt contains a metal different from the metal of saidphotosensitive metal salt.

17. A process as described in claim 14. wherein said color-developingagent is an aromatic primary amino compound.

18. A process as described in claim 14 wherein said reducible heavymetal salt is a salt of a Group VIII metal.

19. A process as described in claim 14 wherein said photosensitive metalsalt is palladium oxalate.

20. A process of providing or intensifying a visible image in aphotographic element which comprises at least one color-forming layerunit containing a photosensitive metal compound which, upon exposure toactinic radiation, forms catalytic sites for the deposition of metalfrom a physical developer solution, said compound comprising an oxide orsulfide of a Group III), IVb, or IVa metal and has associated therewithan image dye-providing photographic color coupler, said processcomprising the steps of 1) imagewise exposing said element to actinicradiation, (2) treating said element with a physical developercomprising a solution of an ionizable salt of a Group Ib, VIa or VIIImetal, (3) contacting the resultant physically developed element in thepresence of a colordeveloping agent with an amplifier composition whichcontains a cobalt(III) complex having a coordination number of six,wherein said contact is maintained under conditions which reducecobalt(III) to cobalt(II) and, in turn, oxidize said color developingagent whereby image dye is formed from the color coupler in said layerunit and the oxidized color developing agent in the areas correspondingto the imagewise distribution of physically deposited heavy metal.

21. A prOCess as described in claim 20 wherein said photosensitivecompound is an oxide of a Group III) metal.

22. A process as described in claim 20 wherein said photosensitivecompound is an oxide of a Group IVa metal.

23. A process as described in claim 20 wherein said photosensitivecompound is a sulfide of a Group IIb metal.

24. A process as described in claim 20 wherein said photosensitivecompound is titanium dioxide.

25. A process as described in claim 20 wherein said ionizable salt is asalt of a Group VIII metal.

26. A process as described in claim 20 wherein said color-developingagent is an aromatic primary amino compound.

27. In a process of developing an imagewise-exposed photographic elementcomprising a support and at least one image dye-providing layer unitthereon which contains a radiation-sensitive metal compound which, uponexposure to actinic radiation, forms catalytic sites for the depositionof metal from a physical developer composition, said compound havingassociated therewith a color coupler, the improvement comprisingphysically developing said imagewise-exposed element to provide animagewise distribution of physically deposited metal and contacting saidphotographic element in the presence of a color developing agent, withan amplifier solution which contains a cobalt(III) metal complex havinga coordination number of 6 under conditions which reduce saidcobalt(III) to cobalt(II) and in turn oxidize said colordeveloping agentto provide an increase in dye density with dye produced from saidcoupler in the areas corresponding to the imagewise distribution of saidmetal.

28. A process as described in claim 27 wherein said compound contains amember selected from the group consisting of a Group Ib, III), IVb, IVa,VIa or VIII metal.

References Cited UNITED STATES PATENTS 3,597,206 8/1971 Yudelson 9648 PD3,655,383 4/1972 Shepard et al 9648 PD FOREIGN PATENTS 777,635 6/1957Great Britain.

RONALD H. SMITH, Primary Examiner R. L. SCHILLING, Assistant ExaminerUS. Cl. X.R.

